In perpendicular magnetic recording (PMR) media with an areal density of 500 Gigabits per square inch (Gb/in2) and beyond, signal to noise ratio (SNR) and write-ability overwrite (OW2) improvements are becoming more and more difficult to realize. While both SNR and OW2 improve when the media is made magnetically softer, the magnetically softer media also results in wider written tracks that degrade adjacent track performance in a drive system.
In order to improve SNR and OW2 without widening written tracks, media structures with dual magnetic recording layers have been explored and discussed, for example, in U.S. Pat. No. 7,488,545 B2 to Fullerton et al. (hereinafter “Fullerton”). In Fullerton, a media structure with two decoupled recording layers is described. The effect of this decoupling of the two recording layers is to double the effective number of grains per unit area in the media. As a result, the SNR of the media is improved because SNR is dependent on the number of grains per unit area.